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In this blog article we are going to take a closer look at the API Standard 671 which specifies the requirements for special purpose couplings used in the petroleum, petrochemical and natural gas industries. This Standard has been developed by the American Petroleum Institute (API), which is not to be confused with the identical abbreviation used in the IT field (Application Programming Interface). Let's begin with a few details about the institute that gave the name to the API Standard. 

Engineers need to consider several aspects for selecting the appropriate coupling such as the type of installation, primary and secondary connection, available space of installation, ease of mounting and dismounting as well as maximum rotational speed and resilience of the coupling. To compensate physical parameters or changes that are not obvious the safety factor, also known as safety multiple or safety coefficient, is taken into account.

The coupling is normally the softest element in the drive line, literally – but by no means the weakest link of the chain. Its configuration plays a decisive role for the functional capability of the driving and driven machine and for the reliability and lifetime of the entire drive system. The optimum adjustment of the coupling to the connected machine units is especially important in all cases where failures and breakdowns are not allowed to occur.